Diversity on a 20 Way or longer CU with many (low utilisation) ring mains Discussion ThreadDiversity on a 20 Way or longer CU with many (low utilisation) ring mains Electrical Advice
Hello,
A quick question which I suspect is becoming more commonly asked as we go towards having more ways in our CUs.
Domestic dwelling, nothing too exuberent but during rejigging the large downstairs ring was split into three and some radials added, as well as seperate feeds to allow for a locationally different oven and induction hob.
Hence there are now quite a few ways for a consumer unit to deal with, but the loading will be very typical of a domestic house.
My question is, with regards to the (rather outdated) diversity theories for a consumer unit, how do the more learned feel about this arrangement:
100A DNO fuse. One sub main on 16 T&E to garage via RCD / Switchfuse.
20 Way Main Switch + SPD consumer unit that is to be populated with RCBOs such:
The RCBOs were chosen to protect the wiring downstream of them, as per normal. The DNO fuse should protect upstream (and, in theory, the tails and Main Switch, which are 100A rated. The CU may also be fed via a 100A Time Delay RCD for backstop protection, as the 30mA RCBOs could allow for a fair bit of commultive earth leakage and its a TT property.
Just wondering if there is any advantage into splitting it into two CUs, though...
Read more
Diversity on a 20 Way or longer CU with many (low utilisation) ring mains for the original thread on Electricians Forums
Hello,
A quick question which I suspect is becoming more commonly asked as we go towards having more ways in our CUs.
Domestic dwelling, nothing too exuberent but during rejigging the large downstairs ring was split into three and some radials added, as well as seperate feeds to allow for a locationally different oven and induction hob.
Hence there are now quite a few ways for a consumer unit to deal with, but the loading will be very typical of a domestic house.
My question is, with regards to the (rather outdated) diversity theories for a consumer unit, how do the more learned feel about this arrangement:
100A DNO fuse. One sub main on 16 T&E to garage via RCD / Switchfuse.
20 Way Main Switch + SPD consumer unit that is to be populated with RCBOs such:
- 40A - Hob 10mm Radial
- 32A - Oven 6mm Radial
- 32A - Kitchen 2.5mm Ring
- 32A - Laundry 2.5mm Ring
- 32A - Downstairs 2.5mm Ring
- 32A - Upstairs 2.5mm Ring
- 32A - Conservatory 2.5mm Ring
- 32A - Immersion 6mm Radial (1x 3kw Locally Switch Fused)
- 25A - Shed 2.5mm SWA
- 20A - Radial Sockets x 2 2.5mm
- 20A - Radial Sockets x 2 2.5mm
- 20A - Radial Socket x 1 2.5mm
- 20A - Fridge x 1 2.5mm
- 20A - Freezer x 1 2.5mm
- 16A - Outside Socket 1.5mm SWA
- 16A - Boiler & Controls 2.5mm (Switchfused Down)
- 6A - Lights Up 1.5mm
- 6A - Lights Down 1.5mm
- 6A - Lights Down 1.5mm
- 6A - Lights Outside 1.5mm
The RCBOs were chosen to protect the wiring downstream of them, as per normal. The DNO fuse should protect upstream (and, in theory, the tails and Main Switch, which are 100A rated. The CU may also be fed via a 100A Time Delay RCD for backstop protection, as the 30mA RCBOs could allow for a fair bit of commultive earth leakage and its a TT property.
Just wondering if there is any advantage into splitting it into two CUs, though...
Read more
Diversity on a 20 Way or longer CU with many (low utilisation) ring mains for the original thread on Electricians Forums
